When Ash, Misty, and Brock run to investigate a mysterious chorus of bells that spontaneously ring out, they meet their old friend Morty and a Pokémon researcher named Eusine. Morty and Eusine discovered that the sacred Crystal Bells, which are said to ring when the legendary Ho-oh returns, are missing. Since the bells were also used to keep peace with the Bug Pokémon living in that area, these Pokémon lash out against their human neighbors, covering the town with their webs. Ash and friends decide to go into the forest and try to find the Crystal Bells.